A Libyan military commander is suing the former Foreign Secretary Jack Straw
over his alleged complicity in illegal rendition and torture.

The civil action, believed to be the first of its kind against such a senior ex minister, could lead to Mr Straw facing a criminal prosecution.

Abdel Hakim Belhadj, 45, is seeking a response to allegations that papers approving his rendition were personally signed off by Mr Straw.

The amount of compensation being sought has not yet been disclosed although lawyers representing Mr Belhadj have said that they are “not ruling anything out”. They argue that "public acknowledgment" and an "admission" of his role by Mr Straw is their main priority.

Today, Sapna Malik, a partner at law firm Leigh Day & Co who is representing Mr Belhadj, said that it was only right "that liability must follow the chain of command".

She added: "The civil action is against Mr Straw personally and seeks his response to allegations that he was complicit in torture and misfeasance in public office.

“If the former Foreign Secretary does not now own up to his role in this extraordinary affair, he will need to face the prospect of trying to defend his position in court.”

Mr Belhadj claims that in 2004, CIA agents took him against his will from Thailand to Libya, via the UK-controlled island of Diego Garcia in the central Indian Ocean.

At that time Mr Belhadj was the leader of the Libyan Islamic Fighting Group (LIFG) and had been living in exile in Beijing, China, after leading opposition to the Gaddafi regime.

MI5 had believed LIFG had close links to al-Qaeda and Mr Belhadj alleges he and his wife, Fatima Bouchar, were detained by American agents in Bangkok as they travelled to the UK to claim political asylum.

The former rebel, also known as Abu Abd Allah Sadiq, says he was tortured during the rendition process itself as well as following his arrival in Libya, where he was subsequently imprisoned.

Earlier this month, it was revealed that the British government had approved the rendition of Mr Belhadj, although it was unclear at exactly what level.

On 15 April, the Sunday Times published an article which quoted sources alleging Mr Straw had personally authorised the process.

Yesterday, Mr Belhadj’s lawyers served papers on Mr Straw, referencing the newspaper article. They claim their case is “further strengthened by a number of documents which came to light after the fall of Colonel Muammar Gaddafi's regime.”

Mr Belhadj, now Tripoli's military council commander, is already suing the UK government, its security forces, and senior MI6 officer Sir Mark Allen, over the same allegations. His lawyers claim their new action against Mr Straw is owing to his position as foreign secretary with responsibility for MI6 at the time of the rendition.

A letter written by Sir Mark to Moussa Koussa, the head of the Libyan Secret Service under Gaddafi, appears to indicate British involvement in Mr Belhadj's rendition as it congratulates the Libyans on his safe arrival in the country.

The letter, dated March 18, 2004, states: “Most importantly, I congratulate you on the safe arrival of Abu Abd Allah Sadiq. This was the least we could do for you and for Libya to demonstrate the remarkable relationship we have built over the years. I am so glad. I was grateful to you for helping the officer we sent out last week.”

They said they had sought a response from the MP for Blackburn by close of business on May 17 "following which proceedings may be issued against you without further notice". Mr Straw has not commented on the matter.

In an interview with BBC Radio 4 last year, he said the Labour government had been opposed to unlawful rendition.

"We were opposed to any use of torture or similar methods," he said. "Not only did we not agree with it, we were not complicit in it and nor did we turn a blind eye to it."

Former Prime Minister Tony Blair has said he has no memory of Mr Belhadj’s case and has claimed he was not aware of any occasion when his government breached its opposition to rendition.